1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a plasma display panel having an improved structure so that visual rays having high brightness is generated at a low discharge voltage and deterioration of a fluorescent substance can be reduced.
2. Description of the Related Art
Plasma display panels are apparatuses for displaying desired numbers, letters or graphic by exciting fluorescent substances by ultraviolet rays generated from plasma.
The plasma display panel is classified into a DC type and an AC type according to the type of a driving voltage applied to a discharge cell, for example, the types of discharge.
In a DC type plasma display panel, all electrodes are exposed to a discharge space so that electric charges are moved directly between the corresponding electrodes. In an AC type plasma display panel, at least one electrode is covered with a dielectric layer and electric charges do not move directly between corresponding electrodes. Instead, discharge is performed by wall charges.
An example of an AC type plasma display panel is shown in FIGS. 1 and 2. Referring to the drawings, a plurality of first electrodes 12 are formed parallel to one another in the first direction on an inner surface of a rear substrate 10. A first dielectric layer 14 is formed on the inner surface of the rear substrate 10 to cover the first electrodes 12. A plurality of barrier ribs 16 for sustaining a discharge distance and preventing electric, optical crosstalk between neighboring discharge cells are formed on an upper surface of the first dielectric layer 14 between the first electrodes 12. Also, a fluorescent substance layer 18 is formed on the upper surface of the first dielectric layer 14 and the side surfaces of the barrier ribs 16.
A front substrate 20 is coupled to the rear substrate 10 to form a discharge space sectioned by the barrier ribs 16. A plurality of second electrodes 13 are formed parallel to one another and perpendicular to the first electrodes 12 on an inner surface of the front substrate 20. A second dielectric layer 15 is formed on the inner surface of the front substrate 20 to cover the second electrodes 13. A protective film 25 is formed on a surface of the second dielectric layer 20. The discharge space formed by coupling the front substrate 20 and the rear substrate 10 is filled with a discharge gas 30 which generates ultraviolet rays during discharge.
The dielectric layers 14 and 15 achieve a high discharge intensity and a memory effect by repeating an electron avalanche phenomenon of wall charges charged on the surface of the dielectric layers. Meanwhile, since the dielectric layers 14 and 15 formed in a thick film method such as print is not dense, plasma intrudes into the dielectric layers through gaps and damages the electrodes (ion bombardment phenomenon). Thus, the protective film 25 prevents the ion bombardment phenomenon and is formed into a dense structure in a thin film method such as deposition. Here, the protective film 25 is formed of MgO having a superior secondary electron emission effect in a deposition method. The MgO protective film not only prevents damage to the dielectric layers due to sputtering of plasma particles, but also lowers a discharge voltage and a sustain voltage by the secondary electron emission. Also, a discharge gas 30 sealed in the discharge space generates ultraviolet rays having a wavelength of about 147 nm during discharge. In general, a penning gas mixture of He, Ne, Ar, or a gas mixture thereof, and a small amount of Xe gas which becomes a source of the generation of ultraviolet rays is used as the discharge gas.
However, the plasma display panel having the above structure cannot prevent deterioration of the fluorescent substance due to ion collision generated on the rear substrate. Also, since the ultraviolet rays are projected toward the rear substrate to excite the fluorescent substance layer and then visual rays generated thereby is reflected by a reflection layer of the rear substrate and projected toward the front substrate, the dielectric layer and electrodes located on the front substrate serve as an obstruction transmission of light so that brightness is lowered.
To solve the above-described problems, it is an object of the present invention to provide a plasma display panel in which a discharge space is filled with a discharge gas including a gas generating ultraviolet rays having a long wavelength during discharge, and a fluorescent substance layer and a protective film are independently formed on each of the front and rear substrates, so that brightness increases, a discharge voltage is reduced, and deterioration of the fluorescent substance is prevented.
To achieve the above object, there is provided a plasma display panel comprising a front substrate and a rear substrate arranged separated a predetermined distance from each other and to face each other, forming a discharge space, a plurality of first electrodes formed on an inner surface of the rear substrate, a first dielectric layer formed on the inner surface of the rear substrate to cover the first electrodes, a plurality of barrier ribs formed between the first electrodes on the inner surface of the rear substrate, sectioning the discharge space, a fluorescent substance layer formed on a surface of the first dielectric layer and side surfaces of the barrier ribs, a first protective film formed on a surface of the fluorescent substance layer, a plurality of second electrodes formed corresponding to the first electrodes on an inner surface of the front substrate, a second dielectric layer formed on the inner surface of the front substrate to cover the second electrodes, a second protective film formed on the surface of the second dielectric layer, and a predetermined discharge gas sealed in the discharge space.
To achieve the above object, there is provided a plasma display panel comprising a front substrate and a rear substrate arranged separated a predetermined distance from each other and to face each other, forming a discharge space, a plurality of first electrodes formed on an inner surface of the rear substrate, a first dielectric layer formed on the inner surface of the rear substrate to cover the first electrodes, a plurality of barrier ribs formed between the first electrodes on the inner surface of the rear substrate, sectioning the discharge space, a first fluorescent substance layer formed on a surface of the first dielectric layer and side surfaces of the barrier ribs, a plurality of second electrodes formed corresponding to the first electrodes on an inner surface of the front substrate, a second dielectric layer formed on the inner surface of the front substrate to cover the second electrodes, a second fluorescent substance layer formed on a surface of the second dielectric layer, a second protective film formed on the surface of the second dielectric layer, and a predetermined discharge gas sealed in the discharge space.
It is preferred in the present invention that the plasma display panel further comprises a first protective film formed on a surface of the first fluorescent substance layer.
It is preferred in the present invention that the discharge gas includes a gas generating ultraviolet rays having a long wavelength of 147 nm or more during discharge.
It is preferred in the present invention that the discharge gas includes a gas generating ultraviolet rays having a long wavelength of 200 nm or more during discharge.
It is preferred in the present invention that the thickness of the first protective film is 100 through 500 nm.
It is preferred in the present invention that the thickness of the second fluorescent substance layer is 1 through 20 xcexcm.